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| United States Patent |
5,142,879
|
|
Nakamura
, et al.
|
September 1, 1992
|
Air conditioning system
Abstract
An air conditioning system for multiple rooms, comprising:
an outdoor unit including a variable delivery compressor, a four way
reversing valve and an outdoor heat exchange unit;
two main connecting pipes composed of a high pressure main pipe and a low
pressure main pipe to connect between outdoors and indoors;
a distribution controller which is connected to the main connecting pipes
to divide them into a high pressure pipe, a low pressure pipe and a medium
pressure pipe therein;
a plurality of indoor units which include indoor heat exchangers,
respectively, which are one end connected to the medium pressure pipe
through electronic expansion valves, respectively, and which are the other
end selectively connected to either one of the high pressure pipe and the
low pressure pipe, respectively;
detecting means for detecting either one of refrigerant temperatures and
refrigerant pressures; and
control means for carrying out a predetermimed control based on such
detection.
| Inventors:
|
Nakamura; Takashi (Kamakura, JP);
Kasai; Tomohiko (Kamakura, JP);
Tani; Hidekazu (Kamakura, JP);
Takata; Shigeo (Kamakura, JP);
Matsuoka; Fumio (Kamakura, JP)
|
| Assignee:
|
Mitsubishi Denki Kabushiki Kaisha (Tokyo, JP)
|
| Appl. No.:
|
672071 |
| Filed:
|
March 19, 1991 |
Foreign Application Priority Data
| Mar 19, 1990[JP] | 2-68955 |
| Apr 23, 1990[JP] | 2-107916 |
| Apr 23, 1990[JP] | 2-107917 |
| Apr 23, 1990[JP] | 2-107930 |
| Current U.S. Class: |
62/160; 62/211; 62/324.6 |
| Intern'l Class: |
F25B 013/00 |
| Field of Search: |
62/160,211,324.6
|
References Cited
U.S. Patent Documents
| 4621505 | Nov., 1986 | Ares et al. | 62/509.
|
| 4878357 | Nov., 1989 | Sekigami et al. | 62/324.
|
| 5040376 | Aug., 1991 | Ueno | 62/324.
|
| Foreign Patent Documents |
| 0316685 | May., 1989 | EP.
| |
| 3220335 | May., 1982 | DE.
| |
| 0057346 | May., 1979 | JP | 62/324.
|
| 62-56429 | Nov., 1987 | JP.
| |
| 1302074 | Dec., 1989 | JP.
| |
| 2194651 | Mar., 1988 | GB.
| |
| 2213248 | Aug., 1989 | GB.
| |
Primary Examiner: Wayner; William E.
Attorney, Agent or Firm: Oblon, Spivak, McClelland, Maier & Neustadt
Claims
What is claimed is:
1. An air conditioning system for multiple rooms, comprising:
an outdoor unit including a variable delivery compressor, a four way
reversing valve and an outdoor heat exchange unit;
two main connecting pipes composed of a high pressure main pipe and a low
pressure main pipe to connect between outdoors and indoors;
a distribution controller which is connected to the main connecting pipes
to divide them into a high pressure pipe, a low pressure pipe and a medium
pressure pipe therein;
a plurality of indoor units which include indoor heat exchangers,
respectively, which are one end connected to the medium pressure pipe
through electronic expansion valves, respectively, and which are the other
end selectively connected to either one of the high pressure pipe and the
low pressure pipe, respectively;
detecting means for detecting either one of refrigerant temperatures and
refrigerant pressures; and
control means for carrying out a predetermined control based on such
detection.
2. An air conditioning system according to claim 1, wherein:
the detecting means is constituted by air temperature sensors for detecting
intake air temperatures Tai at the indoor heat exchangers, and first
refrigerant sensors and second refrigerant sensors for detecting
refrigerant temperatures TR1 at the refrigerant inlets of the indoor heat
exchangers and refrigerant temperatures TR2 at the refrigerant outlets
thereof, respectively; and
the control means controls the electronic expansion valves of the indoor
heat exchangers based on logarithmic mean temperature differences at the
respective indoor heat exchangers, and on desired temperatures and actual
temperatures of rooms with the indoor units installed therein.
3. An air conditioning system according to claim 1, wherein:
the detecting means is constituted by either one of pressure detecting
means for detecting a pressure at a high pressure pipe and a pressure at a
low pressure pipe in the outdoor unit, and temperature detecting means for
detecting a condensing temperature and an evaporating temperature;
there is provided calculation means for making calculation using either one
of the following equations:
##EQU11##
wherein .DELTA.Qcomp is a capacity variable for the compressor,
.DELTA.Ake is a heat exchange capacity variable for the outdoor heat
exchanger, A, B, C, D, A', B', C' and D' are constants, .DELTA.Pd is a
controlled deviation between a desired value and a detected value at the
high pressure pipe in the outdoor unit, .DELTA.Ps is a controlled
deviation between a desired value and a detected value at the low pressure
pipe in the outdoor unit, .DELTA.CT is a controlled deviation between a
desired value and a detected value with respect to the condensing
temperature, and .DELTA.ET is a controlled deviation between a desired
value and a detected value with respect to the evaporating temperature;
and
the control means controls the compressor, the four way reversing valve in
the outdoor unit and the outdoor heat exchange unit based on such
calculation.
4. An air conditioning system according to claim 1, wherein:
the outdoor unit includes an outdoor fan;
the outdoor heat exchange unit comprises a plurality of outdoor heat
exchangers connected in parallel;
at least one of the outdoor heat exchangers is provided with an on-off
valve;
a bypass passage is connected in parallel with the outdoor heat exchangers,
and having an on-off valve therein;
the detecting means is constituted by a high pressure detecting means
arranged in the outdoor unit for detecting a high pressure Pd, and a low
pressure detecting means arranged in the outdoor unit for detecting a low
pressure Ps; and
the control means finds a compressor capacity variable .DELTA.Qcomp and an
outdoor unit heat exchange variable .DELTA.Ak0 based on a controlled
deviation (.DELTA.Pd=Pd*-Pd) between a desired high pressure Pd* and the
detected high pressure, and a controlled deviation (.DELTA.Ps=Ps*-Ps)
between a desired low pressure Ps* and the detected low temperature,
thereby to control the capacity of the compressor based on the found
.DELTA.Qcomp, and also to control the heat exchange capability of the
outdoor heat exchange unit by controlling the on-off valve of the at least
one outdoor heat exchanger, the bypass passage on-off valve and the
outdoor fan based on the found .DELTA.Ak0.
5. An air conditioning system according to claim 1, wherein:
the outdoor unit includes an outdoor fan;
the outdoor heat exchange unit comprises a plurality of outdoor heat
exchangers connected in parallel;
at least one of the heat exchangers is provided with an on-off valve;
a bypass passage is connected in parallel with the outdoor heat exchangers,
and having an on-off valve therein;
the detecting means is constituted by detecting means for detecting a
refrigerant condensing temperature CT and a refrigerant evaporating
temperature ET in the outdoor unit and the indoor units; and
the control means finds a compressor capacity variable .DELTA.Qcomp and an
outdoor unit heat exchange variable .DELTA.Ak0 based on a controlled
deviation (.DELTA.CT=CT*-CT) between a desired condensing temperature CT*
and the detected condensing temperature, and a controlled deviation
(.DELTA.ET=ET*-ET) between a desired evaporating temperature ET* and the
detected evaporating temperature, thereby to control the capacity of the
compressor based on the found .DELTA.Qcomp and, also to control the heat
exchange capability of the outdoor heat exchange unit by controlling the
on-off valve of the at least one outdoor heat exchanger, the bypass
passage on-off valve and the outdoor fan based on the found .DELTA.Ak0.
6. An air conditioning system comprising:
a single outdoor unit including a compressor, a four way reversing valve,
an outdoor heat exchange unit, a variable air volume type of outdoor fan
for feeding air to the outdoor heat exchange unit, and an accumulator;
a first main connecting pipe and a second main connecting pipe;
a plurality of indoor units connected to the outdoor unit through the main
connecting pipes, and including indoor heat exchangers and first flow
controllers;
a first branch joint which is provided with valve systems to selectively
connect one end of the indoor heat exchangers to either one of the first
main connecting pipe and the second main connecting pipe;
a second branch joint which is connected to the other end of the indoor
heat exchangers through the first flow controllers, and which is also
connected to the second main connecting pipe through a second flow
controller;
the first branch joint and the second branch joint being connected together
through the second flow controller;
the second branch joint and the first main connecting pipe being connected
together through a fourth flow controller;
a junction device which includes the first branch joint, the second branch
joint, the second flow controller and the fourth flow controller, and
which is interposed between the outdoor unit and the indoor units;
the outdoor heat exchange unit being constituted by a plurality of outdoor
heat exchangers connected together in parallel and having both ends
provided with electromagnetic on-off valves, and an outdoor bypass passage
connected in parallel with the outdoor heat exchangers and having an
electromagnetic on-off valve therein;
a fourth pressure detecting means arranged at a location between the
outdoor heat exchangers and the four way reversing valve; and
an outdoor unit heat exchange capacity adjusting means for controlling the
air volume of the outdoor fan, the electromagnetic on-off valves at both
ends of the outdoor heat exchangers and the electromagnetic on-off valve
in the outdoor bypass passage so that the pressure detected by the fourth
pressure detecting means achieves a desired pressure.
Description
The present invention relates to an air conditioning system for multiple
rooms which has an outdoor unit and a plurality of indoor units connected
through two refrigerant pipes, and which works as a cooling and heating
concurrent multiple air conditioning system capable of carrying out a
cooling operation mode and a heating operation mode in the respective
indoor units selectively and individually.
Referring to FIG. 17, there is shown a schematic diagram showing a
conventional air conditioning system for multiple rooms, which has been
disclosed in e.g. Japanese Unexamined Patent Publication No. 302074/1989.
In FIG. 17, reference numeral 1 designates an outdoor unit. Reference
numeral 2 designates a variable delivery compressor. Reference numeral 3
designates a four way reversing valve. Reference numeral 4 designates an
outdoor heat exchanger. Reference numeral 5 designates an outdoor
expansion valve. Reference numerals 6a, 6b and 6c designate indoor units.
Reference numerals 8a, 8b and 8c designate indoor heat exchangers.
Reference numeral 9 designates an outdoor fan. Reference numerals 10a, 10b
and 10c designate indoor fans. Reference numeral 11 designates a header.
Reference numerals 12a, 12b and 12c designate indoor first two way valves.
Reference numerals 13a, 13b and 13c designate indoor second two way
valves. Reference numerals 14a, 14b and 14c designate indoor first
expansion valves. Reference numerals 15a, 15b and 15c designate indoor
second expansion valves. Reference numeral 16 designates a two way valves.
The operation of the conventional system will be described. The refrigerant
which has been compressed by the compressor 2 to become a gas having high
temperature and high pressure passes through the four way reversing valve
3, and is partly condensed and liquefied in the outdoor heat exchanger 4
to become a two phase refrigerant having medium pressure. Then it is
transmitted indoors through the outdoor expansion valve 5. When the indoor
unit 6a is under a heating mode, and the indoor units 6b and 6c are under
a cooling mode, the two phase refrigerant which has been forwarded indoors
and has medium pressure passes through the indoor first two valve 12a, and
is condensed and liquified in the indoor heat exchanger 8a. The
refrigerant thus liquefied passes through the indoor second expansion
valve 15a, and is stored as liquid in the header 11. The liquid
refrigerant which has medium pressure passes through the indoor first
expansion valves 14b and 14c of the indoor units 6b and 6c, and enters the
respective indoor heat exchangers 8b and 8c. The refrigerant which has
evaporated in the indoor heat exchangers under low pressure to gasify
returns to the outdoor unit 1a through the indoor second two way valves
13b and 13c. After that, the refrigerant goes back to the compressor 2
again through the four way reversing valve 3. In this manner, a
refrigerant cycle is formed.
The structure of the conventional air conditioning system as stated earlier
requires the capacity control for the compressor 2, the air volume control
for the outdoor fan 9, the control for the outdoor expansion valve 5, the
control for the outlet expansion valve 15a of the indoor unit 6a under the
heating mode, and the control for the inlet expansion valves 14b and 14c
of the indoor units 6b and 6c under the cooling mode. This creates a
problem wherein signals required for these controls are transmitted to and
fro between the indoor units and the outdoor unit to complicate these
controls, failing in reliability and performance stability.
On the other hand, there has been known a heat pump type air conditioning
system wherein a single heat source device is connected to a plurality of
indoor units through two pipes, i.e., a gas pipe and liquid pipe, and
wherein either heating or cooling is carried out in all indoor units at
the same time.
Since this conventional multi-room heat pump type air conditioning system
has been constructed as stated above, all indoor units can carry out
either one of heating and cooling at the same time which creates a problem
wherein a room required for cooling is subjected to heating, and wherein a
room required for heating is subjected to cooling. In particular, when
such air conditioning system is installed in a large-scale building, the
problem as stated just above is serious because interior zones and
perimeter zones, or ordinary office rooms and office-automated rooms such
as computer rooms are totally different in terms of air conditioning load.
It is an object of the present invention to solve the first problem, and to
provide an air conditioning system for multiple rooms capable of
simplifying controls, and of improving reliability and performance
stability.
It is an object of the present invention to solve the second problem, and
to provide a multi-room heat pump type air conditioning system wherein a
single heat source device is connected to a plurality of indoor units, and
the respective indoor unit can selectively and individually carry out
either cooling or heating, whereby even if interior zones and perimeter
zones, or ordinary office rooms and office-automated rooms such as
computer rooms are totally different in terms of air conditioning load in
the case of installment of the system in a large-scale building, the
system can cope with the requirements of cooling and heating the spaces
with the respective indoor units installed in them.
In order to attain the first object, the present invention provides an air
conditioning system for multiple rooms, comprising an outdoor unit
including a variable delivery compressor, a four way reversing valve and
an outdoor heat exchange unit; two main connecting pipes composed of a
high pressure main pipe and a low pressure main pipe to connect between
outdoors and indoors; a distribution controller which is connected to the
main connecting pipes to divide them into a high pressure pipe, a low
pressure pipe and a medium pressure pipe therein: a plurality of indoor
units which include indoor heat exchangers, respectively, which one end
connected to the medium pressure pipe through electronic expansion valves,
respectively, and which are the other end selectively connected to either
one of the high pressure pipe and the low pressure pipe, respectively;
detecting means for detecting either one of refrigerant temperatures and
refrigerant pressures; and control means for carrying out a predetermined
control based on such detection.
According to an aspect of the present invention, the detecting means
constituted by air temperature sensors for detecting intake air
temperatures Tai at the indoor heat exchangers, and first refrigerant
sensors and second refrigerant sensors for detecting refrigerant
temperatures T.sub.R1 at the refrigerant inlets of the indoor heat
exchangers and refrigerant temperatures T.sub.R2 at the refrigerant
outlets thereof, respectively; and the control means controls the
electronic expansion valves of the indoor heat exchangers based on
logarithmic mean temperature differences at the respective indoor heat
exchangers, and on desired temperatures and the actual temperatures for
rooms with the indoor units installed therein.
According to another aspect of the present invention, the detecting means
is constituted by either one of pressure detecting means for detecting a
pressure at a high pressure pipe and a pressure at a low pressure pipe in
the outdoor unit, and temperature detecting means for detecting a
condensing temperature and an operating temperature; there is provided
calculation means for making calculation using either one of the following
equations:
##EQU1##
(Wherein .DELTA.Q.sub.comp is a capacity variable for the compressor,
.DELTA.Ake is heat exchange capacity variable for the outdoor heating
exchanger, A, B, C, D, A', B', C' and D' are constants, .DELTA.Pd is a
control led deviation between a desired value and a detected value at the
high pressure pipe in the outdoor unit, .DELTA.Ps is a control led
deviation between a desired value and a detected value at the low pressure
pipe in the outdoor unit, .DELTA.CT is a control led deviation between a
desired value and a detected value with respect to the condensing
temperature, and .DELTA.ET is a control led deviation between a desired
value and a detected value with respect to the evaporating temperature;
and the control means controls the compressor, the four way reversing
valve in the outdoor unit and the outdoor heat exchanger unit based on
such calculation.
According to a further aspect of the present invention, the outdoor unit
includes an outdoor fan; the outdoor heat exchange unit comprises a
plurality of outdoor heat exchangers connected in parallel; at least one
of the outdoor heat exchangers is provided with an on-off valve; a bypass
passage is connected in parallel with the outdoor heat exchangers, and
having an on-off valve therein; the detecting means is constituted by a
high pressure detecting means arranged in the outdoor unit for detecting a
high pressure Pd, and a low pressure detecting means arranged in the
outdoor unit for detecting a low pressure Ps; and the control means finds
a compressor capacity variable .DELTA.Q.sub.comp and an outdoor unit heat
exchange variable .DELTA.Ak.sub.0 based on a control led deviation
(.DELTA.Pd=Pd*-Pd) between a desired high pressure Pd* and the detected
high pressure, and a control led deviation (.DELTA.Ps=Ps*-Ps) between a
desired low pressure Ps* and the detected low pressure, thereby to control
the capacity of the compressor based on the found .DELTA.Q.sub.comp, and
also to control the heat exchange capability of the outdoor heat exchange
unit by controlling the on-off valve of the at least one outdoor heat
exchanger, the bypass passage on-off valve and the outdoor fan based on
the found .DELTA.Ak.sub.0.
According to a still further aspect of the present invention, the outdoor
unit includes an outdoor fan; the outdoor heat exchange unit comprises a
plurality of outdoor heat exchangers connected in parallel; at least one
of the heat exchangers is provided with an on-off valve; a bypass passage
is connected in parallel with the outdoor heat exchangers, and having an
on-off valve therein; the detecting means is constituted by detecting
means for detecting a refrigerant condensing temperature CT and a
refrigerant evaporating temperature ET in the outdoor unit and the indoor
units; and the control means finds a compressor capacity variable
.DELTA.Q.sub.comp and an outdoor unit heat exchange variable
.DELTA.Ak.sub.0 based on a controlled deviation (.DELTA.CT=CT*-CT) between
a desired condensing temperature CT* and the detected condensing
temperature, and a controlled deviation (.DELTA.ET=ET*-ET) between a
desired evaporating temperature ET* and the detected evaporating
temperature, thereby to control the capacity of the compressor based on
the found .DELTA.Q.sub.comp, and also to control the heat exchange
capability of the outdoor heat exchange unit by controlling the on-off
valve of the at least one outdoor heat exchanger, the bypass passage
on-off valve and the outdoor fan based on the found .DELTA.Ak.sub.0.
In order to attain the second object, the present invention also provides
an air conditioning system comprising a single outdoor unit including a
compressor, a four way reversing valve, an outdoor heat exchange unit, a
variable air volume type of outdoor fan for feeding air to the outdoor
heat exchange unit, and an accumulator; a first main connecting pipe and a
second main connecting pipe; a plurality of indoor units connected to the
outdoor unit through the main connecting pipes, and including indoor heat
exchangers and first flow controllers; a first branch joint which is
provided with valve systems to selectively connect one end of the indoor
heat exchangers to either one of the first main connecting pipe and the
second main connecting pipe; a second branch joint which is connected to
the other end of the indoor heat exchangers through the first flow
controller, and which is also connected to the second connecting pipe
through a second flow controller; the first branch joint and the second
branch joint being connected together through the second flow controller;
the second branch joint and the first main connecting pipe being connected
together through a fourth flow controller; a junction device which
includes the first branch joint, the second branch joint, the second flow
controller and the fourth flow controller, and which is interposed between
the outdoor unit and the indoor unit; the outdoor heat exchanger unit
being constituted by a plurality of outdoor heat exchangers connected
together in parallel and having both ends provided with electromagnetic
on-off valves, and an outdoor bypass passage connected in parallel with
the outdoor heat exchangers and having an electromagnetic on-off valve
therein; a fourth pressure detected means arranged at location between the
outdoor heat exchangers and the four way reversing valve; and an outdoor
unit heat exchange capacity adjusting means for controlling the air volume
of the outdoor fan, the electromagnetic on-off valves at both ends of the
outdoor heat exchangers and the electromagnetic on-off valve in the
outdoor bypass passage so that the pressure detected by the fourth
pressure detecting means achieves a desired pressure.
In drawings:
FIG. 1 is a schematic diagram of a first embodiment of the air conditioning
system according to the present invention;
FIGS. 2a, 2b and 2c are graphs to help explain the operation controls of
the first embodiment;
FIG. 3 is a schematic diagram of a second embodiment;
FIG. 4 is a control block diagram of the second embodiment;
FIG. 5 is a schematic diagram of a third embodiment;
FIG. 6 is a control block diagram of the third embodiment;
FIG. 7 is a drawing of graphs to help explain the operation control of the
third embodiment;
FIG. 8 is as schematic diagram of the air conditioning system of a fourth
embodiment;
FIG. 9 is a schematic diagram of the air conditioning system of a fifth
embodiment;
FIG. 10 is a schematic diagram showing the operation states of the fifth
embodiment of FIG. 9 wherein sole operation on cooling and sole operation
on heating are performed;
FIG. 11 is a schematic diagram showing the operation states of the fifth
embodiment of FIG. 9 wherein heating is principally performed when heating
load is greater than cooling load;
FIG. 12 is a schematic diagram showing the operation states of the fifth
embodiment of FIG. 9 wherein cooling is principally performed when cooling
load is greater than heating load;
FIG. 13 is a schematic diagram showing the air conditioning system of a
sixth embodiment;
FIG. 14 is a schematic diagram showing a system for adjusting the heat
exchange capacity in the outdoor unit of the fifth embodiment;
FIGS. 15 and 16 are flow charts for the system for adjusting the heat
exchange capacity in the outdoor unit of the fifth embodiment; and
FIG. 17 is a schematic diagram showing a conventional air conditioning
system for multiple rooms.
The present invention will be described in detail with reference to
preferred embodiments illustrated in the accompanying drawings.
A first embodiment of the present invention will be described with
reference to the drawings. In FIG. 1, reference numeral 1 designates an
outdoor unit. Reference numeral 2 designates a variable delivery
compressor which is arranged in the outdoor unit 1. Reference numeral 3
designates a four way reversing valve. Reference numerals 4a and 4b
designate outdoor heat exchangers. Reference numerals 6a-6c designate
indoor units. Reference numeral 7 designates an accumulator. Reference
numerals 8a-8c designate indoor heat exchangers. Reference numerals
12a-12c designate electronic expansion valves which are connected to each
one end of the indoor heat exchangers 8a-8c. Reference numerals 17 and 18
designate main connecting pipes which connect between the outdoor unit 1
and a distributive controller 19. Reference numeral 20 designates a high
pressure pipe which is arranged in the distributive controller 19.
Reference numeral 21 designates a low pressure pipe. Reference numeral 22
designates a medium pressure pipe. Reference numeral 23 designates an
electronic expansion valve. Reference numerals 24a-24c and 25a-25c
designate electromagnetic on-off valves. The distributive controller 19 is
connected to the respective indoor units 6a-6c through two branch pipes,
respectively. The respective indoor units 6a-6c have the one end connected
to the medium pressure pipe 22 of the distributive controller 19 through
the corresponding electronic expansion valves 12a-12c, respectively. The
respective indoor units have the other end connected to the high pressure
pipe 20 and the low pressure pipe 21 through the electromagnetic on-off
valves 24a-24c and 25a-25c of the distributive controller 19,
respectively.
The indoor units 6a-6c are provided with air temperature sensors 26a-26c
for detecting the temperature of intake air, respectively. The indoor
units 6a-6c are also provided, respectively, with first refrigerant
temperature sensors 27a-27c and second refrigerant temperature sensors
28a-28c for detecting the refrigerant inlet and outlet temperature at the
opposite ends of the heat exchangers 8a-8c. The indoor units 6a-6c include
microcomputers 29a-29c, respectively, which work as control means to
control the electronic expansion valves 12a-12c based on detection
temperature signals from these sensors, and actual temperatures and set
temperatures for each room.
In the air conditioning system having such structure, the operations which
are made when the indoor unit 6a is under a heating operation mode, and
the indoor units 6b and 6c are under a cooling operation mode will be
described.
The refrigerant which has been compressed by the compressor 2 in the
outdoor unit 1 to become a gas having high temperature and high pressure
passes through the four way reversing valve 3, and is partly condensed in
the outdoor heat exchangers 4a and 4b to become a two phase refrigerant.
The two phase refrigerant enters the indoor distributive controller 19
through the main connecting pipe 17 having high pressure. The high
pressure gaseous refrigerant which has been separated in a gas-liquid
separator 30 passes through the high pressure gas pipe 20, and enters the
indoor unit 6a through the electromagnetic on-off valve 25a to be used in
the indoor heat exchanger 8a for heating. After that, the refrigerant
enters the medium pressure pipe 22 through the electronic expansion valve
12a. The refrigerant joins with the refrigerant which has come into the
medium pressure pipe 22 from a liquid layer portion in the gas-liquid
separator 30 through the electronic expansion valve 23. The refrigerant
thus joined enters the indoor units 6b and 6c. The refrigerant is
depressurized by the electronic expansion valves 12 b and 12c, and is used
in the indoor heat exchangers 8b and 8c for cooling to be gasified. After
that, the refrigerant joins together in the low pressure pipe 21 through
the electromagnetic on-off valves 24b and 24c, comes out of the
distributive controller 19, and enters the main pipe 18 which directs the
refrigerant outdoors. Then, the refrigerant passes through the four way
reversing valve 3 and the accumulator 7 in the outdoor unit 1, and returns
to the compressor 2 again. In this manner, a refrigerant circuit for
cooling and heating concurrent operation is formed.
In the refrigerant circuit, the heat exchanger 8a in the indoor unit 6a
works as a condenser whereas the heat exchangers 8b and 8c in the indoor
units 6b and 6c function as evaporators.
The capability control for the respective indoor units 6a-6c under such
operations is made as follows: The indoor unit 6a is exemplified for
illustration. The temperature Tai of the air which is inspired into the
indoor unit 6a is detected by the air temperature sensor 26a, the
temperature T.sub.R2 at the refrigerant inlet side of the indoor heat
exchanger 8a is detected the second refrigerant temperature sensor 28a,
and the temperature T.sub.R1 at the refrigerant outlet side of the indoor
heat exchanger 8a is detected by the first refrigerant temperature sensor
27a. Detection temperature signals indicative of the temperatures detected
by the sensors are transmitted to the microcomputer 29a. The microcomputer
29a can find a logarithmic mean temperature difference .DELTA.tm in the
indoor heat exchanger 8a, using the equation (1):
##EQU2##
The logarithmic mean difference .DELTA.tm is considered as indication of
the capability of the heat exchanger, and the capability control of the
indoor unit 6a is carried out based on the logarithmic mean temperature
difference .DELTA.tm. Specifically, the temperature changes from the
refrigerant inlet to the refrigerant outlet of the condenser are as shown
in FIG. 2a. The capability Q of the condenser is substantially represented
by
Q=A.multidot.K.multidot..DELTA.tm
wherein A represents a heat exchange area (m.sup.2), and K represents an
over-all heat transfer coefficient (kcal/h.multidot..degree.C.). The
capability Q can be considered as being proportional to the logarithmic
mean temperature difference .DELTA.tm. In the FIG. 2a, the refrigerant
flows in the direction of arrows.
This means that the control based on the temperature difference .DELTA.tm
enables the capability control. Such control is carried out as follow: A
required indoor unit capability is determined from the correlation as
shown in FIG. 2b, depending on a controlled deviation .DELTA.Ti between an
actual room temperature T.sub.R and a set temperature T.sub.s for the room
where the indoor unit 6a is installed. A logarithmic mean temperature
difference, i.e., desired logarithmic mean temperature difference
.DELTA.tm* which corresponds to a required indoor unit capability Qc can
be found from the correlation as shown in FIG. 2c. .DELTA.tm can be
brought closer to .DELTA.tm* to carry out a desired capability control,
which can be realized by controlling the opening angle of the electronic
expansion valve 12a. For example, if the electronic expansion valve 12a is
further throttled, the temperature changes in the indoor heat exchanger
8a-exhibits so-called sub-cooling to become as indicated by a dashed line
in FIG. 2a. As a result, the refrigerant outlet temperature which is
detected by the first refrigerant temperature sensor 27a lowers from
T.sub.R1 to T.sub.R1 ' to decrease .DELTA.tm, allowing the Capability Qc
to lessen.
On the other hand, when a heat exchanger is operated as an evaporator, the
opening angle of a corresponding electronic expansion valve is controlled
to exert a influence on the superheat at the refrigerant outlet, allowing
to the capability control to be carried out. Such controls can be
performed at the respective indoor heat exchangers to carry out an
autonomous capability control at the respective indoor heat exchangers. An
autonomous capability control can be also made at the outdoor unit 1 to
dispense with the signal transmission between the indoor units and the
outdoor unit.
In accordance with the first embodiment, the intake air temperature Tai,
the refrigerant inlet temperature T.sub.R1 and the refrigerant outlet
temperature T.sub.R2 are detected by the air temperature sensor, and the
first and second refrigerant temperature sensors at the respective heat
exchangers. The logarithmic mean temperature difference .DELTA.tm at each
heat exchanger is found by the corresponding control means based on the
detected temperatures. Because the logarithmic mean temperature difference
.DELTA.tm substantially corresponds to the capability of each heat
exchanger at that time, the electronic expansion valve which is connected
to each heat exchanger can be controlled based on .DELTA.tm, the set room
temperature for each room and the actual room temperature in each room to
carry out the autonomous capability control at each room.
As explained, in accordance with the first embodiment, the respective
indoor heat exchangers are provided with the sensors for detecting the
intake air temperature, the refrigerant inlet temperature and the
refrigerant outlet temperature, and the logarithmic mean temperature
difference at the respective heat exchangers is found based on the
detected temperatures. The electronic expansion valve which is connected
to each indoor heat exchanger is controlled based on the logarithmic mean
temperature difference, the actual room temperature and the set room
temperature for the room. This arrangement allows the autonomous
capability control to be made at each indoor unit, and a decentralized
control to be performed among the indoor units, offering the advantage of
obtaining an air conditioning system for multiple rooms capable of
improving reliability and stabilizing operation performance.
Now, a second embodiment of the present invention will be described.
Referring now to FIG. 3, there is shown a schematic diagram of the
refrigerant circuit of the air conditioning system for multiple rooms
according to the second embodiment. In the second embodiment, an outdoor
unit 1 includes a high pressure detector 38 and a low pressure detector
39, from which detection signals are inputted into a controller 15 as
shown. The controller 15 controls compressor 2, and a four way reversing
valve 3, and the heat exchange capability of an outdoor heat exchanger 4
through a fan 9. Reference numeral 7 designates an accumulator.
In the refrigerant circuit, the high pressure detector 38 is arranged at a
high pressure pipe in the outdoor unit 1, and the low pressure detector 39
is arranged at a low pressure pipe in the outdoor unit 1. The controller
15 receives signals from both detectors 38 and 39 to carry out the
delivery control for the compressor 2, to control the heat exchange
capability of the outdoor heat exchanger 4 through revolution control of
the fan 9, and to perform the switching control of the four way reversing
valve 3 by performing operations as to whether the indoor heat exchanger 4
is operated as a condenser to be used for a radiating source, or is
operated as an evaporator to be used for a heat absorbing source.
In general, if the capability of the compressor 2 is increased, a high
pressure Pd raises, and a low pressure Ps lowers. If the capability of the
evaporator is increased, both high pressure Pd and low pressure Ps raise.
To the contrary, if the capability of the condenser is increased, both
high pressure Pd and low pressure Ps lowers. The relationship among them
can be quantified to obtain the following equation:
##EQU3##
wherein a,b,c,d>0, .DELTA.Pd=Pd*-Pd, .DELTA.Ps=Ps*-Ps (Pd* and Ps* are
desired values, and Pd and Ps are detected values.), .DELTA.Q.sub.comp is
a capability variable of the compressor 2, and .DELTA.Ake is a heat
exchange capability variable of the outdoor heat exchanger. The equation
can be modified as:
##EQU4##
Referring now to FIG. 4, there is shown a schematic control block diagram
wherein the equation is represented in the form of diagram. The controller
15 carries out the controls of respective parts based on the result of the
operations.
A condensing temperature CT and an evaporating temperature ET may be
utilized instead of the high pressure Pd and the low pressure Ps. At that
case, sensors for detecting the condensing temperature and the evaporating
temperature are required. The equation at that case is as follows:
##EQU5##
wherein, .DELTA.CT=CT*-CT, .DELTA.ET=ET*-ET, CT* and ET* are desired
values, and CT and ET are detected values.
In accordance with the second embodiment, the pressures at the high
pressure pipe and the low pressure pipe in the outdoor unit, or the
condensing temperature and the evaporating temperature in the outdoor unit
are detected, and the compressor capability variable and the heat exchange
capability variable of the outdoor heat exchanger are calculated based on
the controlled deviation between the detected values and the desired
values. Based on the result of the calculation, the delivery control of
the compressor in the outdoor unit, the control for the heat exchange
capability of the outdoor heat exchanger, and the switching control of the
four way reversing valve are carried out.
As explained, in accordance with the second embodiment, in the air
conditioning system which has a cooling and heating concurrent multiple
refrigerant circuit using two pipes, the controls for the outdoor
compressor and the outdoor heat exchanger can be carried out based on only
the temperature or the pressure detected in the outdoor unit. No
information about the indoor units is required to enable an autonomous
decentrialized controls for the indoor units and the outdoor unit,
improving reliability and stabilizing operation performance.
Now, a third embodiment of the present invention will be described.
Referring now to FIG. 5, there is shown a schematic diagram showing the
refrigerant circuit of the air conditioning system according to the third
embodiment. In the third embodiment, on-off valves 26a, 26b, 27a and 27b,
a bypass passage 48 and a bypass on-off valve 49 are arranged in an
outdoor unit 1 as shown.
The on-off valves 26a, 26b, 27a and 27b are connected to both ends of
outdoor hear exchangers 4a and 4b, the bypass passage 48 is arranged in
parallel with the outdoor hear exchangers 4a and 4b, and the bypass on-off
valve 49 is arranged in the bypass passage 48.
In addition, the reference numeral 38 designates a high pressure detector
which is arranged at the refrigerant outlet side of a variable delivery
compressor 2 to detect the pressure Pd of the refrigerant at that
location. Reference numeral 39 designates a low pressure detector which is
arranged at the refrigerant inlet side of an accumulator 7 to detect the
pressure Ps of the refrigerant at that location. Reference numeral 15
designates a controller which controls a four way reversing valve 3, an
outdoor fan 9, the on-off valves 26a, 26b, 27a and 27b, and the bypass
on-off valve 49 based on the detection outputs from the high pressure
detector 38 and the low pressure detector 39. Reference numeral 36
designates a four way reversing valve.
In the air conditioning system of the third embodiment, when an indoor unit
6a is under heating mode and outdoor units are under cooling mode, a heat
exchanger 8a of the indoor unit 6a works as condenser and heat exchangers
8b and 8c of the indoor units 6b and 6c function as evaporator.
In the operation of the third embodiment, the heat exchange capability
required for the outdoor unit 1 changes depending on a change in the
capability of the indoor units 6a-6c, or the switching from the heating
mode to the cooling mode and vice versa in the indoor units. This means
that the heat exchange capability of the outdoor unit 1 has to be
controlled accordingly. In the third embodiment, a signal indicative of
the high pressure Pd detected by the high pressure detector 38, and a
signal indicative of the low pressure Ps detected by the low pressure
detector 39 are transmitted to the controller 15. In general, if the
compressor capability is increased, the high pressure Pd raises, and the
low pressure Ps lowers. On the other hand, if the evaporation capability
is increased, both high pressure Pd and low pressure Ps raise. To the
contrary, if the condenser capability is increased, both high pressure Pd
and low pressure Ps lower. If there is such a steady state that the high
pressure Pd and the low pressure Ps keep certain values, it can be
considered that the hear exchange capability of the indoor units is
balanced against that of the outdoor unit. This means that if the heat
exchange capability of the outdoor unit 1 is controlled in a way to bring
the high pressure Pd and the low pressure Ps closer to a predetermined
desired high pressure Pd* and a predetermined desired low pressure Ps*,
respectively, an autonomous control can be realized in the outdoor unit 1
in a closed form. If a variable for the compressor capability Q.sub.comp
is represented by .DELTA.Q.sub.comp, and if a variable for the heat
exchange capability Ak.sub.0 of the outdoor hear exchanger is represented
by .DELTA.Ak.sub.0, the relationship between Pd and Ps is expressed as the
following equation (2):
##EQU6##
wherein a, b, c and d are predetermined constants, and .DELTA.Pd and
.DELTA.Ps are controlled deviations to the desired values, despectively,
i.e.
.DELTA.Pd=Pd*-Pd, .DELTA.Ps=Ps*-Ps.
The equation (2) can be modified as follows:
##EQU7##
Based on .DELTA.Q.sub.comp thus found, the delivery control of the
compressor 2 is carried out. In addition, based on .DELTA.Q.sub.comp thus
found, it is determined whether the outdoor heat exchangers 4a and 4b are
operated as condensers to be used for radiating source or are operated as
evaporators to be used for hear absorbing source. Based on the result of
this determination, four way reversing valves 3 and 36 are controlled. For
example, under the operation states as stated earlier, if the heat
exchange capability obtained by the previous heat exchange capability and
the newly found heat exchange capability is positive, the refrigerant
circuit takes such cycle that the outdoor heat exchangers 4a and 4b work
as evaporators. If the heat exchange capability thus obtained is negative,
the refrigerant circuit takes such cycle that the outdoor heat exchangers
4a and 4b work as condensers. Variable control for the heat exchange
capability at these cycles (AKe for positive, and AKc for negative) is
made by controlling the revolutions of the outdoor fan 9 and carrying out
the on-off control of the on-off valves 26a, 26b, 27a and 27b, and the
bypass valve 49. In other words, depending on the found heat exchange
capability, the selection of the outdoor heat exchangers to be activated
is made, and whether bypassing the refrigerant through the bypass passage
48 is required or not is determined. In addition, the revolution of the
outdoor fan 9 is adjusted to continuously control the heat exchange
capability. Referring now to FIG. 6, there is shown a schematic control
block diagram showing such control.
For example, if the outdoor heat exchangers 4a and 4b work as condensers,
whether to use both outdoor heat exchangers 4a and 4b or to use only the
outdoor heat exchanger 4b, and whether to use the outdoor heat
exchanger(s) while bypassing a part of the refrigerant through the bypass
passage 48 are determined depending on a required heat exchange
capability. According to such determination, the on-off controls of the
on-off valves 26a, 26b, 27a and 27b, and the bypass valve 49 are made, and
the revolution of the outdoor fan 9 is controlled. Referring now to FIG.
7, there is shown the relationship between the revolution of the outdoor
fan and the heat exchange capability of the condenser(s) at the respective
cases. The case wherein both outdoor heat exchangers 4a and 4b are used
has the greatest value for AKc, with the case wherein only the outdoor
heat exchanger 4b is used, and the case wherein the bypass passage 48 is
used for bypass following in that order. In addition, the values for AKc
successfully change with respect to the revolutions of the outdoor fan 9
in the respective cases.
Such controls can be adopted to realize an autonomous capability control in
the outdoor unit 1.
Referring now to FIG. 8, there is shown a schematic diagram of the air
conditioning system of a fourth embodiment wherein a refrigerant
condensing temperature CT and a refrigerant evaporating temperature ET in
the whole system are detected instead of the high pressure Pd and the low
pressure Ps to control the outdoor unit 1. Reference numeral 34 designates
refrigerant temperature sensors which are arranged in indoor units 6a-6c,
respectively.
Reference numeral 35 designates microcomputers which control electronic
expansion valves 12a-12c based on temperatures detected by the refrigerant
temperature sensors 34 to carry out autonomous controls of the indoor
units 6a-6c. Reference numeral 46 designates a temperature sensor which is
arranged on an outdoor hear exchanger 4b. In this embodiment, the greatest
value among the temperatures detected by the refrigerant temperature
sensors 34 and the temperature sensor 46 is taken as the condensensing
temperature CT, and the least value is taken as the evaporating
temperature ET. A controlled deviation .DELTA.CT between the condensensing
temperature CT and a desired condensensing temperature CT*, and a
controlled deviation .DELTA.ET between the evaporating temperature ET and
a desired evaporating temperature ET* are found, respectively. Like the
control based on the high pressure Pd and the low pressure Ps,
.DELTA.Q.sub.comp and .DELTA.AK.sub.0 are found from the following
equation:
##EQU8##
The heat exchange capability may be controlled in a similar manner.
Although in that case there is e.g. a manner wherein the highest
temperature and the lowest temperature are selected by the microcomputers
35 or the like in the indoor units, and these temperatures are transmitted
to the outdoor unit to be compared to the detection temperature in the
outdoor unit, at least one signal transmission line is required between
the indoor units and the outdoor unit. However, the provision of the
temperature sensors offers advantage over that of the pressure detectors
in terms of cost.
The air conditioning system according to the third embodiment collects the
high pressure Pd and the low pressure Ps by the pressure sensors in the
form of real time measurement, and calculates the controlled deviation
.DELTA.Pd and .DELTA.Ps to the desired high pressure Pd* and the desired
low pressure Ps* in the refrigeration cycle. In addition, the system finds
a product by multiplying the constant matrix
##EQU9##
and takes the calculation result as
##EQU10##
Based on such result, the heat exchange capability of the outdoor heat
exchangers is controlled.
As explained, the third embodiment has such arrangement that the controls
of the compressor, the outdoor heat exchangers and the four way reversing
valve in the outdoor unit are made based on detection on only the high
pressure and the low pressure in the outdoor unit. This arrangement
enables the autonomous decentralized controls in the indoor units and the
outdoor unit, offering an advantage in that reliability is improved and
operation performance is stabilized.
Like the fourth embodiment, the condensensing temperature and the
evaporating temperature, instead of the high pressure and the low
pressure, in the refrigerant cycle may be detected for the autonomous
decentralized controls to stabilize the operation of the outdoor unit.
Now, a fifth and a sixth embodiment of the present invention will be
described.
Referring now to FIG. 9, there is shown a schematic diagram of the entire
structure of the fifth embodiment of the air conditioning system according
to the present invention, which is depicted on the bases of the
refrigerant system of the air conditioning system. Referring to FIGS. 10
through 12, there are shown schematic diagrams showing the operation
states under the cooling and heating modes according to the fifth
embodiment of FIG. 9, FIG. 10 showing the operation states wherein sole
operation on cooling and sole operation on heating are performed, FIGS. 11
and 12 showing the operation states of a cooling and heating concurrent
operation, FIG. 11 showing the operation states wherein heating is
principally performed (heating load is greater than cooling load), and
FIG. 12 showing the operation state wherein cooling is principally
performed (cooling load is greater than heating load). Referring now to
FIG. 13, there is shown a schematic diagram showing the entire structure
of a sixth embodiment of the air conditioning system which is depicted on
the bases of the refrigerant system of the air conditioning system.
Although explanation on these embodiments will be made for the case
wherein a single heat source device is connected to three indoor units,
the following explanation is also applicable to the case wherein a single
source device is connected two or more indoor units.
In FIG. 9, reference numeral A designates the heat source device. Reference
numerals B, C and D designate the indoor units which are connected in
parallel with one another as described later on, and which have the same
structures. Reference numeral E designates a junction device which
includes a first branch joint 10, a second flow controller 13, a second
branch joint 11, a gas-liquid separator 12, heat exchanging portions 16a,
16b, 16c, 16d and 19, a third flow controller 15, and a fourth flow
controller 17.
Reference numeral 1 designates a compressor. Reference numeral 2 designates
a four way reversing valve which can switch the flow direction of a
refrigerant in the heat source device. Reference numeral 3 designates an
outdoor heat exchange unit which is installed in the heat source device.
Reference numeral 4 designates an accumulator which is connected to the
compressor 1, the reversing valve 2 and the outdoor heat exchange unit 3.
Reference numeral 20 designates a variable air volume type of outdoor fan
which is installed in the heat source device to feed air to the outdoor
heat exchange unit 3. The heat source device A is constituted by these
members. Reference numeral 5 designates indoor heat exchangers which are
arranged in the three indoor unit B, C and D. Reference numeral 6
designates a first connecting pipe which is large in diameter, and which
connects the four way reversing valve 2 in the heat source device A to the
junction device E. Reference numerals 6b, 6c and 6d designate first branch
pipes which connect the indoor heat exchangers 5 in the indoor units B, C
and D to the junction device E, respectively, and which correspond to the
first main connecting pipe 6. Reference numeral 7 designates a second main
connecting pipe which connects the outdoor exchange unit 3 in the heat
source device A to the junction device E, and which is smaller than the
first main connecting pipe in diameter. Reference numerals 7b, 7c and 7d
designate second branch pipes which connect the indoor heat exchangers 5
in the indoor units B, C and D to the junction device E, respectively, and
which are arranged at the side of the indoor units to correspond to the
second main pipe 7. Reference numeral 8 designates three way switching
valves which can selectively connect the first branch pipes 6b, 6c and 6d
to either the first main pipe 6 or the second main pipe 7. Reference
numeral 9 designates first flow controllers which are connected to the
respective indoor heat exchangers 5 in close proximity to the same, which
are controlled based on superheat amounts on cooling and sub-cooling
amounts on heating at outlet sides of the respective indoor heat
exchangers 5, and which are connected to the second branch pipes 7b, 7c
and 7d, respectively. Reference numeral 10 designate the first branch
joint which is constituted by the three way switching valves 8 which can
selectively the first branch pipes 6b, 6c and 6d to either the first main
pipe 6 or the second main pipe 7. Reference numeral 11 designates the
second branch joint which includes the second branch pipes 7b, 7c and 7d
for the indoor units, and the second main pipe 7. Reference numeral 12
designates the gas-liquid separator which is arranged in the second main
pipe 7, and which has a gas layer zone connected to first ports 8a of the
respective switching valves 8 and a liquid layer zone connected to the
second branch joint 11. Reference numeral 13 designates the second flow
controller (an electric expansion valve in the embodiment) which is
connected between the gas-liquid separator 12 and the second branch joint
11, and which can be selectively opened and closed. Reference numeral 14
designates a bypass pipe which connects the second branch joint 11 to the
first main pipe 6. Reference numeral 15 designates the third flow
controller (an electric expansion valve in the embodiment) which is
arranged in the bypass pipe 14. Reference numeral 16a designates the
second heat exchanging portion which is arranged in the bypass pipe 14
downstreams of the third flow controller 15, and which carries out heat
exchange with the confluence of the second branch pipes 7b, 7c and 7d for
the indoor units in the second branch joint 11. Reference numerals 16b,
16c and 16d designate the third heat exchanging portions which are
arranged downstream of the third flow controller 15 in the bypass pipe 14,
and which carries out heat exchange with the second branch pipes 7b, 7c
and 7d for the indoor units in the second branch joint 11. Reference
numeral 19 designates the first heat exchanging portion which is arranged
downstream of the third flow controller 15 in the bypass pipe 14 and
downstream of the second heat exchanging portion 16a, and which carries
out heat exchange with a pipe connecting between the gas-liquid separator
12 and the second flow controller 13. Reference numeral 17 designates the
fourth flow controller (an electric expansion valve in the embodiment)
which connects between the second branch joint 11 and the first main pipe
6 so as to be selectively opened and closed. Reference numeral 32
designates a third check valve which is arranged between the outdoor
exchange unit 3 and the second main pipe 7, and which allows the
refrigerant only to flow from the outdoor exchange unit 3 to the second
main pipe 7. Reference numeral 33 designates a fourth check valve which is
arranged between the four way reversing valve 2 in the heat source device
A and the first main pipe 6, and which allows the refrigerant only to flow
from the first main pipe 6 to the four way reversing valve 2. Reference
numeral 34 designates a fifth check valve which is arranged between the
four way reversing valve 2 in the heat source device A and the second main
connecting pipe 7, and which allows the refrigerant only to flow from the
four way reversing valve 2 to the second main connecting pipe 7. Reference
numeral 35 designates a sixth check valve which is arranged between the
outdoor exchange unit 3 and the first main connecting pipe 6, and which
the refrigerant only to flow from the first main connecting pipe 6 to the
outdoor exchange unit 3. The third, the fourth, the fifth and the sixth
check valves 32, 33, 34 and 35 form a check valve unit 40. Reference
numeral 25 designates a first pressure detecting means which is arranged
between the first branch joint 10 and the second flow controller 13.
Reference numeral 26 designates a second detecting means which is arranged
between the second flow controller 13 and the fourth flow controller 17.
The outdoor heat exchange unit 3 is constituted by a first outdoor heat
exchanger 41, a second outdoor heat exchanger 42 connected in parallel
with the first outdoor heat exchanger 41 and having the same heating
surface area as the first outdoor heat exchanger 41, a heat source device
bypass passage 43, a first electromagnetic on-off valve 44 arranged at one
end of the first outdoor heat exchanger 41 for connection with the four
way reversing valve 2, a second electromagnetic on-off valve 45 arranged
at the other end of the first outdoor heat exchanger 41, a third
electromagnetic on-off valve 46 arranged at one end of the second outdoor
heat exchanger 42 for connection with the four way reversing valve 2, a
fourth electromagnetic on-off valve 47 arranged at the other end of the
second outdoor heat exchanger 42, and a fifth electromagnetic on-off valve
48 arranged in the heat source device bypass passage 43. Reference numeral
18 designates a fourth pressure detecting means which is arranged in a
pipe which connects between the four way reversing valve 2 and the outdoor
heat exchange unit 3. The pipe is under high pressure on cooling mode and
under low pressure on heating mode.
The operation of the fifth embodiment will be described. Firstly, the
operation in a sole cooling mode will be explained, referring to FIG. 10.
As indicated by arrows of solid line in FIG. 10, the refrigerant which has
been discharged from the compressor 1 to become a gas having high
temperature and high pressure passes through the four way reversing valve
2, and carries out heat exchange with the air fed by the variable air
volume type outdoor fan 20 at the outdoor heat exchange unit 3, where the
refrigerant is condensed to be liquefied. After that, the refrigerant thus
liquefied passed through the third check valve 32, the second main
connecting pipe 7, the gas-liquid separator 12 and the second flow
controller 13 in that order, and enters the respective indoor units B, C
and D through the second branch joint 11 and the second branch pipes 7b,
7c and 7d for the indoor units. The refrigerant which has entered the
indoor units B, C and D is depressurized by the flow controllers 9 which
are controlled based on the superheat amounts at the outlets of the
respective indoor heat exchangers 5. The refrigerant which has been
depressurized to have low pressure by the flow controllers 9 carries out
heat exchange, at the indoor heat exchangers 5, with the air in the room
with the corresponding heat exchangers therein. As a result of the heat
exchange, the refrigerant is evaporated and gasified, causing the rooms to
be cooled. The refrigerant thus gasified passes through the first branch
pipes 6b, 6c and 6d for the indoor units, the three way switching valves
8, the first branch joint 10, the first main connecting pipe 6, the fourth
check valve 33, the four way reversing valve 2 in the heat source device,
and the accumulator 4, and is inspired into the compressor 1. In this
manner, a circulation cycle is formed to carry out cooling. At that time,
the three way switching valves 8 have the first ports 8a closed, and
second ports 8b and third ports 8c opened. At that time, the first main
connecting pipe 6 is at low pressure in it, and the second main connecting
pipe 7 is at high pressure in it, which necessarily make the third check
valve 32 and the fourth check valve 33 to conduct.
In addition, in this mode, the refrigerant which has passed through the
second flow controller 13 partly enters the bypass pipe 14 where the
entered part of the refrigerant is depressurized to low pressure by the
third flow controller 15. The refrigerant thus depressurized carries out
heat exchange with the second branch pipes 7b, 7c and 7d at the third heat
exchanging portions 16b, 16c and 16d in the second branch joint 11, with
the confluence of the second branch pipes 7b, 7c and 7d for the indoor
units at the second heat exchanging portion 16a in the second branch joint
11 and at the first heat exchanging portion 19 with the refrigerant which
will enter the second flow controller 13. The refrigerant is evaporated
due to such heat exchange, passes through the first main connecting pipe 6
and the fourth check valve 33, and is inspired into the compressor 1
through the outdoor four way reversing valve 2 and the accumulator 4. On
the other hand, the refrigerant, which has heat exchanged at the first,
the second and the third heat exchanging portions 19, 16a, 16b, 16c and
16d, and has been cooled so as to get sufficient sub-cooling in the second
branch joint 11, enters the indoor units B, C and D which are expected to
carry out cooling.
The operation in a sole heating mode will be explained, referring to FIG.
10. As indicated in by arrows of dotted line, the refrigerant which bas
been discharged from the compressor 1 to become a gas having high
temperature and high pressure passes through the four way reversing valve
2, passes through the fifth check valve 34, the second main connecting
pipe 7 and the gas-liquid separator 12, and passes through the first
branch joint 10, the three way switching valves 8, the first branch pipes
6b, 6c and 6d for the indoor units in that order. Then, the refrigerant
enters the respective indoor units B, C and D where carries out heat
exchange with the air in the rooms to be condensed and liquefied, causing
the rooms to be heated. The refrigerant thus liquefied passes through the
first flow controllers 9 which are controlled to be substantially fully
opened based on sub-cooling amounts at the outlets of the respective
indoor heat exchangers 5. Then, the refrigerant enters the second branch
joint 11 through the second branch pipes 7b, 7c and 7d for the indoor
units, and joins together. In addition, the joined refrigerant passes
through the fourth flow controller 17. The refrigerant is depressurized by
either the first flow controller 9, or the third and the fourth flow
controllers 13 and 17 to take a two phase state having low pressure. The
refrigerant thus depressurized passes through the first main connecting
pipe 6 and the sixth check valve 35 in the heat source device A, and
enters the outdoor heat exchange unit 3, where the refrigerant carries out
heat exchange with the air fed by the variable air volume type of outdoor
fan 20. The refrigerant which has been evaporated and gasified due to such
heat exchange is inspired into the compressor 1 through the four way
reversing valve 2 in the heat source device, and the accumulator 4. In
that manner, a circulation cycle is formed to carry out heating. At that
mode, the three way switching valves 8 have the second ports 8b closed,
and the first ports 8a and the third ports 8c opened. At that time, the
first main connecting pipe 6 is at low pressure in it, and the second main
connecting pipe 7 is at high pressure in it, which necessarily allows the
refrigerant to flow through the fifth check valve 34 and the sixth check
valve 35.
Thirdly, the case wherein heating is principally performed in cooling and
heating concurrent operation will be explained, referring to FIG. 11.
As indicated by arrows of dotted line, the refrigerant which has been
discharged from the compressor 1 to become a gas having high temperature
and high pressure is forwarded to the junction device E through the fifth
check valve 34 and the second main connecting pipe 7. The refrigerant
passes through the gas-liquid separator 12, passes through the first
branch joint 10, the three way switching valves 8 and the first branch
pipes 6b and 6c for the indoor units in that order, and enters the
respective indoor units B and C which are expected to carry out heating.
The refrigerant carries out heat exchange, at the indoor heat exchangers
5, with the air in the room with the indoor units B and C therein, and is
condensed and liquefied to heat the rooms. The refrigerant thus condensed
and liquefied passes through the first flow controllers 9 which are
controlled to be substantially fully opened based on sub-cooling amounts
at the outlets of the indoor heat exchangers of the indoor units B and C,
is slightly depressurized by the first flow controllers 9, and enters the
second branch joint 11. The refrigerant which has entered the second
branch joint 11 partly passes through the second branch pipe 7d and enters
the indoor unit D which is expected to carry out cooling. The refrigerant
enters the first flow controller 9 which is controlled based on superheat
amount at the outlet of the indoor heat exchanger of the indoor unit D,
and is depressurized therein. After that, the refrigerant thus
depressurized enters the indoor heat exchanger 5, and carries out heat
exchange to be evaporated and gasified, causing the room to be cooled.
Then, The refrigerant goes into the first main connecting pipe 6 through
the three way switching valve 8.
On the other hand, the remaining refrigerant passes through the fourth flow
controller 17 which is controlled in a way to bring the pressure
difference between the detected pressure by the first pressure detecting
means 25 and that by the second pressure detecting means 26 into a
predetermined range. That refrigerant joins with the refrigerant which has
passed through the cooling indoor unit D, passes through the first main
connecting pipe 6 and the sixth check valve 35 in the heat source device
A, and enters the outdoor heat exchange unit 3 where the refrigerant
carries out heat exchange with the air fed by the outdoor fan 20. The
refrigerant is evaporated and gasified due to such heat exchange. The heat
exchange amount can be arbitrarily obtained at the outdoor heat exchange
unit 3 by adjusting the air volume from the outdoor fan 20 in a way to
bring the detected pressure by the fourth pressure detecting means 18 to a
predetermined desire pressure, carrying out the on-off controls of the
first, the second, the third and the fourth electromagnetic on-off valve
44, 45, 46 and 47 at the opposite ends of the first and the second outdoor
heat exchangers 41 and 42 to adjust heating surface area, and carrying out
the on-off control of the electromagnetic on-off valve 48 in the heat
source device bypass passage 43 to adjust the flow rate of the refrigerant
which can pass through the first and the second outdoor heat exchangers 41
and 42. The refrigerant is inspired into the compressor 1 through the four
way reversing valve 2 in the heat source device and the accumulator 4. In
that manner, a circulation cycle is formed to carry out the cooling and
heating concurrent operation wherein heating is principally performed. At
that time, the pressure difference between the evaporating pressure in the
indoor heat exchanger 5 of the cooling indoor unit D, and the pressure in
the outdoor heat exchange unit 3 becomes smaller because switching to the
first main connecting pipe 6 having a greater diameter is made. In
addition, at that time, the three way switching valve 8 which are
connected to the indoor units B and C have the second ports 8b closed, and
the first ports 8a and the third ports 8c opened. The three way switching
valve 8 which is connected to the cooling indoor unit D has the first port
8a closed, and the second port 8b and the third port 8c opened. Further,
at that time, the first main connecting pipe 6 is at low pressure in it,
and the second main connecting pipe 7 is at high pressure in it, which
necessarily allows the refrigerant to flow through the fifth check valve
34 and the sixth check valve 35.
In addition, during this cycle, a part of the liquid refrigerant goes from
the confluence of the second branch pipes 7b, 7c and 7d in the second
branch joint 11 into the bypass pipe 14, is depressurized to a low
pressure by the third flow controller 15, carries out heat exchange, at
the third heat exchanging portions 16b, 16c and 16d, with the second
branch pipes 7b, 7c and 7d in the second branch joint 11, and, at the
second heat exchanging portion 16a, with the confluence of the second
branch pipes 7b, 7c and 7d in the second branch joint 11. The refrigerant,
which has been evaporated due to such heat exchange, passes through the
first main connecting pipe 6 and the sixth check valve 35, and is inspired
into the compressor 1 through the four way reversing valve 2 in the heat
source device and the accumulator 4. On the other hand, the refrigerant
which has carried out heat exchange at the second and third heat
exchanging portions 16a, 16b, 16c and 16d, and has been cooled to obtain
sufficient sub-cooling enters the indoor unit D which is expected to carry
out cooling.
The case wherein cooling is principally performed in cooling and heating
concurrent operation will be explained, referring to FIG. 12.
As indicated by arrows of solid line, the refrigerant gas which has been
discharged from the compressor 1 enters the outdoor heat exchange unit 3,
where the refrigerant gas carries out heat exchange with the air fed by
the variable air volume type outdoor fan 20, taking a two phase state
having high temperature and high pressure. An arbitrary heat exchange
amount can be obtained at the outdoor heat exchange unit 3 by adjusting
the air volume from the outdoor fan 20 in a way to bring the pressure
detected by the fourth pressure detecting means 18 to a predetermined
desired pressure, carrying out the on-off operations of the first, second,
third and fourth electromagnetic on-off valves 44, 45, 46 and 47 at the
opposite ends of the first and second outdoor heat exchangers 41 and 42 to
adjust a heating surface area, and carrying out the on-off operation of
the electromagnetic on-off valve 48 in the heat source device bypass
passage 43 to adjust the flow rate of the refrigerant which flows through
the first and second outdoor heat exchangers 41 and 42. After that, the
refrigerant which has taken such two phase state passes through the third
check valve 32 and the second main connecting pipe 7, and is forwarded to
the gas-liquid separator 12 in the junction devide E. In the gas-liquid
separator, the refrigerant is separated into a gaseous refrigerant and a
liquid refrigerant. The gaseous refrigerant passes through the first
branch joint 10, the three way switching valve 8 and the first branch pipe
6d in that order, and enters the indoor unit D which is expected to carry
out heating. The gaseous refrigerant carries out heat exchange, at the
indoor heat exchanger 5, with the air in the room, and is condensed and
liquefied to heat the room. In addition, the refrigerant thus liquefied
passes through the first flow controller 9 which is controlled based on
the sub-cooling amount at the outlet of the indoor heat exchanger 5 to be
substantially fully opened, and the refrigerant is slightly depressurized.
Then, the refrigerant enters the second branch joint 11. On the other
hand, the liquid refrigerant as remainder passes through the second flow
controller 13 which is controlled based on the pressure detected by the
first pressure detecting means 25 and that by the second pressure
detecting means 26. The refrigerant enters the second branch joint 11, and
joins the refrigerant which has passed through the heating indoor unit D.
Then, the combined refrigerant passes through the second branch joint 11
and the second branch pipes 7b and 7c in that order, and enters the indoor
units B and C. The refrigerant which has entered the indoor units B and C
is depressurized by the first flow controllers 9 which are controlled
based on the superheat amounts at the outlets of the indoor heat
exchangers B and C. The refrigerant thus depressurized carries out heat
exchange with the air in the rooms to be evaporated and gasified, cooling
the rooms. In addition, the refrigerant thus gasified passes through the
first branch pipes 6b and 6c, the three way switching valve 8 and the
first branch joint 10, and is inspired into the compressor 1 through the
first main connecting pipe 6, the fourth check valve 33, the four way
reversing valve 2 in the heat source device and the accumulator 4. In this
manner, a circulation cycle is formed to carry out the cooling and heating
concurrent operation wherein cooling is principally performed. In that
time, the three way switching valves 8 which are connected to the indoor
units B and C have the first ports 8a closed, the second ports 8b and the
third ports 8c opened. The three way switching valve 8 which is connected
to the indoor unit D has the second port 8b closed, and the first port 8a
and the third port 8c opened. In addition, at that time, the first main
connecting pipe 6 is at a low pressure in it, and the second main
connecting pipe 7 is at a high pressure in it, which necessarily allows
the refrigerant to flow through the third check valve 32 and the fourth
check valve 33.
During this cycle, a part of the liquid refrigerant goes from the
confluence of the second branch pipes 7b, 7c and 7d into the bypass pipe
14 in the second branch joint 11, is depressurized by the third flow
controller 15, and carries out heat exchange, at the third heat exchanging
portions 16b, 16c and 16d, with the second branch pipes 7b, 7c and 7d in
the second branch joint 11, with the confluence of the second branch pipes
7b, 7c and 7d at the second heat exchanging portion 16a in the second
branch joint 11, and, at the first heat exchanging portion 19, with the
refrigerant which will enter into the second flow controller 13. That part
of the liquid refrigerant has been evaporated due to such heat exchange
passes through the first main connecting pipe 6 and the fourth check valve
33, and is inspired into the compressor 1 through the four way reversing
valve 2 of the heat source device and the accumulator 4. On the other
hand, the refrigerant which has been heat exchanged at the first, second
and third heat exchanging portions 19, 16a, 16b, 16c and 16d, and has been
cooled to obtain sufficient sub-cooling in the second branch joint 11
enters the indoor units B and C which are expected to carry out cooling.
Now, the controls for the outdoor fan 20, and the first, second, third,
fourth and fifth electromagnetic on-off valves 44, 45, 46, 47 and 48 will
be explained for the case of the cooling and heating concurrent operation.
Referring now to FIG. 14, there is shown a schematic diagram showing a
control system for the outdoor fan 20, and the first, second, third,
fourth and fifth electromagnetic on-off valves 44, 45, 46, 47 and 48.
Reference numeral 28 designates outdoor unit heat exchange capacity
adjusting means which controls the air volume from the outdoor fan 20 and
the on-off controls of the first, second, third, fourth and fifth
electromagnetic on-off valves 44, 45, 46, 47 and 48, depending on the
pressure detected by the fourth pressure detecting means 18. Referring now
to FIG. 15, there is shown a flow chart showing the control contents of
the outdoor unit heat exchange capacity adjusting means for the case of
the cooling and heating concurrent operation wherein cooling is
principally performed. Referring now to FIG. 16, there is shown a flow
chart of the control contents of the outdoor unit heat exchange capacity
adjusting means 28 for the case of the cooling and heating concurrent
operation wherein heating is principally performed.
The outdoor unit heat exchange capacity adjusting manner which is made by
the outdoor unit heat exchange capacity adjusting means 28 will be
explained. In the embodiment, the heat exchange capacity is adjusted by
one of the following four stages.
The first stage corresponds to a case wherein the greatest heat exchange
capacity is required. The first, second, third and fourth electromagnetic
on-off valves 44-47 are opened, and the fifth electromagnetic on-off valve
48 is closed, causing the refrigerant to flow through both outdoor heat
exchangers 41 and 42, and preventing the refrigerant from passing through
the heat source device bypass passage 43. The air volume from the outdoor
fan 20 is adjusted between stoppage and full speed by an inverter or the
like (not shown). In that case, if there is an external wind such as
airflow around building, rather great heat exchange is made even if the
outdoor fan is stopped. This means that the cooling capability under the
concurrent operation wherein heating is principally performed, and the
heating capability under the concurrent operation wherein cooling is
principally performed become insufficient. In addition, if there is no
external wind, it is impossible to obtain heat exchange capacity not
higher than the heat exchange amount by natural convection. This means
that if the temperature difference between the external temperature and
the condensensing or evaporating temperature of the refrigerant at the
outdoor heat exchange unit 3 is great, the cooling capability under the
concurrent operation wherein heating is principally performed, and the
heating capability under the concurrent operation wherein cooling is
principally performed become insufficient.
The second stage corresponds to a case wherein the second greatest heat
exchange capacity is required. The first and second electromagnetic on-off
valves 44 and 45 are opened, and the third, fourth and fifth
electromagnetic on-off valves 46-48 are closed, causing the refrigerant to
pass through only the first outdoor heat exchanger 41, and preventing the
refrigerant from passing through the second outdoor heat exchanger 42 and
the heat source device bypass passage 43. The heating surface area of the
outdoor heat exchange unit 3 is reduced by half in that manner. The air
volume from the outdoor fan 20 is adjusted between stoppage and full speed
by an inverter or the like (not shown). In that case, the heat exchanging
amount due to an external wind such as airflow around building can be
reduced by half, and the heat exchanging amount due to natural convection
at the absence of an external wind can be also reduced by half. This means
that the shortage of the cooling capability under the concurrent operation
wherein heating is principally performed, and the shortage of the heating
capability under the concurrent operation wherein cooling is principally
performed have no significant influence.
The third stage corresponds to a case wherein heat exchange capacity
smaller than that in the second stage is required. The first, second and
fifth electromagnetic on-off valves 44, 45 and 48 are opened, and the
third and fourth electromagnetic on-off valves 46 and 47 are closed,
causing the refrigerant to pass through the first outdoor heat exchanger
41 and the heat source device bypass passage 43, and preventing the
refrigerant from passing through the second outdoor heat exchanger 42. In
that manner, the heating surface area of the outdoor heat exchange unit 3
is reduced by half, and flow rate of the refrigerant to the first outdoor
heat exchanger 41 is decreased. The air volume from the outdoor fan 20 is
adjusted between stoppage and full speed by an inverter or the like (not
shown). In that case, the heat exchanging amount due to an external wind
such as airflow around building can be further decreased in comparison
with the second stage. In addition, the heat exchanging amount due to
natural convection at the absence of external wind can be also decreased.
As a result, the shortage of the cooling capability under the concurrent
operation wherein heating is principally performed, and the shortage of
the heating capability under the concurrent operation wherein cooling is
principally performed can be minimized.
The fourth stage corresponds to a case wherein the smallest heat exchanging
amount is required. The fifth electromagnetic on-off valve 48 is opened,
and the first, second, third and fourth electromagnetic on-off valves
44-47 are closed, causing the heat exchanging amount at the outdoor heat
exchange unit 3 to become zero. In that case, there is not the heat
exchanging amount due to an external wind such as airflow around building
at all. There is no shortage of the cooling capability under the
concurrent operation wherein heating is principally performed, or no
shortage of the heating capability under the concurrent operation wherein
cooling is principally performed. Even if there is an external wind, the
first stage and the second stage can be successively controlled, provided
that the heat exchanging amount AK2.sub.MAX of the heat source device
which is obtained when the outdoor fan 20 is at full speed is greater than
the heat exchange capacity AK1.sub.MIN which is obtained at the first
stage when there is an external wind and the outdoor fan 20 is stopped,
i.e., the wind speed of the external wind satisfies the relation,
AK2.sub.MAX >AK1.sub.MIN. Likewise, even if there is an external wind, the
second stage and the third stage can be also successively controlled,
provided that the heat exchanging capacity AK3.sub. MAX in the heat source
device which is obtained at the third stage when the outdoor fan 20 is at
full speed is greater than the heat exchange capacity AK2.sub.MIN which is
obtained when there is an external wind and the outdoor fan 20 is stopped
at the second stage, i.e., the wind speed of the external wind satisfies
the relation, AK3.sub.MAX >AK2.sub.MIN. As explained, even if there is
some external wind, the heat exchange capacity of the heat source device
can be adjusted in the four stages in the manner as stated earlier to
obtain successive heat exchange capacity at the heat source device,
obtaining sufficient cooling capability under the concurrent operation
wherein heating is principally performed, and sufficient heating
capability under the concurrent operation wherein cooling is principally
performed, without causing a high pressure to be extraordinarily increased
or low pressure to be extraordinarily decreased.
Now, the control content of the outdoor unit heat exchange capacity
adjusting means 28 which is made under the concurrent operation wherein
cooling is principally performed will be explained, referring to the flow
chart of FIG. 15.
At Step 50, a pressure P detected by the pressure detecting means 18 is
compared to a predetermined first desired pressure P1. If P>P1, the
program proceeds to Step 51. At Step 51, it is judged whether the outdoor
fan 20 is at full speed or not. If negative, the program proceeds to Step
52 where air volume is increased. Then the program returns to Step 50. If
affirmative, the program proceeds to Step 53 where it is judged whether
the electromagnetic on-off valves 44 and 45 are opened or not. If
negative, the program proceeds to Step 54 where both electromagnetic
on-off valves 44 and 45 are opened to activate the first outdoor heat
exchanger 41. Then, the program returns to Step 50. If affirmative, the
program proceeds to Step 55 where it is judged whether the electromagnetic
on-off valve 48 is opened or not. If affirmative, the program proceeds to
Step 56 where the electromagnetic on-off valve 48 is closed to inactivate
the heat source device bypass passage 43. Then the program returns to Step
50. If negative, the program proceeds to Step 57 where it is judged
whether the electromagnetic on-off valves 46 and 47 are opened or not. If
negative, the program proceeds to Step 58 where the electromagnetic on-off
valves 46 and 47 are opened to activate the second outdoor heat exchanger
42. Then, the program returns to Step 50. Even if affirmative, the program
returns to Step 50. On the other hand, if the inequation, P.ltoreq.P1, is
satisfied at Step 50, the program proceeds to Step 60. At Step 60, the
pressure P detected by the pressure detecting means 18 is compared to a
predetermined second desired pressure P2 which is set to be smaller than
the first desired pressure. If P<P2, the program proceeds to Step 61. If
P.gtoreq. P2, the program returns to Step 50. At Step 61, it is judged
whether the outdoor fan 20 is stopped or not. If negative, the program
proceeds to Step 62 where the air volume is decreased. Then the program
returns to Step 50. If affirmative, the program proceeds to Step 63 where
it is judged whether the electromagnetic on-off valves 46 and 47 are
opened or not. If affirmative, the program proceeds to Step 64 where the
electromagnetic on-off valves 46 and 47 are closed to inactivate the
second outdoor heat exchanger 42. Then, the program returns to Step 50. If
negative, the program proceeds to Step 65 where it is judged whether the
electromagnetic on-off valve 48 is opened or not. If negative, the program
proceeds to Step 66 where the electromagnetic on-off valve 48 is opened to
activate the heat source device bypass passage 43. Then the program
returns to Step 50. If affirmative, the program proceeds to Step 67 where
it is judged whether the electromagnetic on-off valves 44 and 45 are
opened or not. If affirmative, the program proceeds to Step 68 where the
electromagnetic on-off valves 44 and 45 are closed to inactivate the first
outdoor heat exchanger 41. Then the program returns to Step 50. Even if
negative, the program returns to Step 50. In that manner, the pressure P
detected by the pressure detecting means 18 can be brought between P1 and
P2.
Next, the control contents of the outdoor unit heat exchange capacity
adjusting means 28 which is made under the concurrent operation wherein
heating is principally performed will be explained, referring to FIG. 16.
At Step 70, the pressure P detected by the pressure detecting means 18 is
compared to a predetermined third desired pressure P3. If P<P3, the
program proceeds to Step 71. On the other hand, the inequation,
P.gtoreq.P3, is satisfied at Step 70, the program proceeds to Step 80. At
Step 80, the pressure P detected by the pressure detecting means 18 is
compared to a predetermined fourth desired pressure P4 which is set to be
greater than the third desired pressure. If P>P4, the program proceeds to
Step 81. If P.ltoreq.P4, the program returns to Step 70. The processes
which will be made at Steps 71-78 and 81-88 after the program has
proceeded to Step 71 or Step 81 are the same as the processes at Steps
51-58 and 61-68 of FIG. 15, and explanation of these Steps will be omitted
for the sake of simplicity. In that manner, the pressure P detected by the
pressure detecting means 18 can take a value between P3 and P4.
Although in the fifth embodiment the three way switching valves 8 can be
provided to selectively connect the first branch pipes 6b, 6c and 6d to
either the first main connecting pipe 6 or the second main connecting pipe
7, paired on-off valves such as solenoid valves 30 and 31 can be provided
instead of three way switching valves as shown as the sixth embodiment in
FIG. 13 to make selective switching, offering similar advantage.
In addition, although in the fifth embodiment the outdoor heat exchange
unit 3 is constituted by the two outdoor heat exchangers equal to each
other in terms of heating surface area, the outdoor heat exchangers may
not be equal to each other in terms of heating surface area, or three or
above of outdoor heat exchangers are used to constitute the outdoor heat
exchange unit.
Further, although in the fifth embodiment the number of the outdoor heat
exchangers which is opened when the heat source device bypass passage 43
is opened is not greater than 1, the number of the outdoor heat exchangers
which are opened when the heat source device bypass passage 43 is opened
may be two or more.
In the fifth and sixth embodiments, under the concurrent operation wherein
heating is principally performed, the gaseous refrigerant which has high
pressure is introduced from the heat source device check valve unit, the
second main connecting pipe and the first branch joint into the indoor
units which are expected to carry out heating. After that, the refrigerant
partly goes from the second branch joint into the indoor unit which is
expected to carry out cooling. The refrigerant carries out cooling in that
indoor unit, and enters the first main connecting pipe through the first
branch joint. On the other hand, the remaining refrigerant passes through
the fourth flow controller, joins with the refrigerant which has passed
through the cooling indoor unit, and enters the first main connecting
pipe. Then the refrigerant returns to the heat source device check valve
unit, carries out heat exchange at an arbitrary amount at the outdoor heat
exchange unit, and returns to the compressor again. In addition, such
arbitrary amount of heat exchange can be obtained at the outdoor heat
exchange unit by adjusting the air volume from the outdoor fan in a way to
bring the pressure detecting by the fourth pressure detecting means to the
predetermined desired pressure, carrying out the on-off controls of the
electromagnetic on-off valves at the opposite ends of the plural outdoor
heat exchangers to adjust heating surface area, and carrying out the
on-off control of the electromagnetic on-off valve in the heat source
device bypass passage to adjust the flow rate of the refrigerant which
flows through the plural outdoor heat exchangers.
Under the concurrent operation wherein cooling is principally performed,
the gaseous refrigerant which has high pressure is heat exchanged at the
heat source device in an arbitrary amount to take a two phase. The
refrigerant which has taken such two phase passes through the second main
connecting pipe, and is separated into a gas and a liquid. The gaseous
refrigerant thus separated is introduced through the first branch joint
into the heating indoor unit to carry out heating there. Then the
refrigerant enters the second branch joint. On the other hand, the
remaining refrigerant which is the liquid refrigerant separated passes
through the second flow controller, and joins, at the second branch joint,
which the refrigerant which has passed through the heating indoor unit.
The combined refrigerant enters the cooling indoor units to carry out
cooling there. After that, the refrigerant is directed from the first
branch joint to the heat source device check valve unit through the first
main connecting pipe, and returns to the compressor again. An arbitrary
amount of heat exchange can be obtained at the outdoor heat exchange unit
by adjusting the air volume from the outdoor fan in a way to bring the
pressure detected by the fourth detecting means to the predetermined
desired pressure, carrying out the on-off controls of the electromagnetic
on-off valves at the opposite ends of the plural outdoor heat exchangers
to adjust heating surface area, and carrying out the on-off control of the
electromagnetic on-off valve in the heat source device bypass passage to
adjust the flow rate of the refrigerant which flows through the plural
outdoor heat exchangers.
Under sole heating operation, the refrigerant is introduced from the heat
source device check valve unit into the indoor units through the second
main connecting pipe and the first branch joint to carry out heating at
the indoor units. Then the refrigerant returns from the second branch
joint to the heat source device check valve unit through the fourth flow
controller and the first main connecting pipe.
Under sole cooling operation, the refrigerant is introduced from the heat
source device check valve unit into the indoor units through the second
main connecting pipe and the second branch joint to carry out cooling at
the indoor units. Then the refrigerant returns from the first branch joint
to the heat source device check valve unit through the first main
connecting pipe.
As explained in the air conditioning system according to the fifth and
sixth embodiments, the single heat source device which is constituted by
the compressor, the four way reversing valve, the outdoor heat exchange
unit, the variable air volume type of outdoor fan for feeding air to the
heat exchange unit, and an accumulator is connected, through the first and
second main connecting pipes, to the plural indoor units which are
constituted by the indoor heat exchangers and the first flow controllers.
The first branch joint which includes the valve system capable of
selectively connecting one of the indoor heat exchanger of each indoor
unit to either the first main connecting pipe or the second main
connecting pipe is connected through the second flow controller to the
second branch joint which is connected to the other end of the indoor heat
exchanger of each indoor unit through the first flow controllers and is
also connected to the second main connecting pipe through the second flow
controller. The junction device which houses the first branch joint, the
second branch joint, the second flow controller and the fourth flow
controller is interposed between the heat source device and the plural
indoor units. In such arrangement, the outdoor heat exchange unit is
constituted by the plural outdoor heat exchangers connected in parallel to
each other and having electromagnetic on-off valves at the opposite ends,
and the heat source device bypass passage connected in parallel with the
outdoor heat exchangers and having the electromagnetic on-off valve in it.
The fourth pressure detecting means is arranged between the outdoor heat
exchange unit and the outdoor four way reversing valve. There is provided
the outdoor unit heat exchange capacity adjusting means which can control
the air volume from the outdoor fan, the on-off operations of the
electromagnetic on-off valves at the opposite ends of the plural outdoor
heat exchangers, and the on-off control of the electromagnetic on-off
valve in the heat source device bypass passage is a way to bring the
pressure detected by the fourth pressure detecting means to the
predetermined pressure. As a result, the plural indoor units can
selectively and independently carry out cooling and heating at the same
time. Some of the indoor units can carry out cooling while the other
indoor units can carry out heating at the same time. In addition, the one
which has a greater diameter between the main pipes for extending to
connect between the heat source device and the junction device can always
utilized at the side of low pressure, thereby improving capability. In
particular, in the case wherein heating is principally performed under the
concurrent operation, the main pipe having a greater diameter can be
utilized at the side of low pressure to decrease the difference between
the evaporating pressure of the indoor heat exchanger(s) of cooling indoor
unit(s) and that in the outdoor heat exchanger. As a result, the
evaporating pressure in the indoor heat exchanger(s) can be increased to
prevent cooling capability from being short. In addition, the evaporating
pressure at the outdoor heat exchanger can be lowered to prevent the heat
exchanger from being iced and capability from lowering in operation.
Further, even if there is a great difference between an external air
temperature and the condensation or evaporating temperature of the
refrigerant at the outdoor heat exchange unit, or there is some external
air, the heat exchange capacity at the heat source device can be obtained
at a successive form. As a result, the pressure at the high pressure side
is prevented from extraordinarily raising, and the pressure at the low
pressure side is prevented from extraordinarily lowering. The cooling
capability under the concurrent operation wherein heating is principally
performed, and the heating capability under the concurrent operation
wherein cooling is principally performed can be obtained in a sufficient
form.
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